It would be nice to be able to restrict the ability of users to set the fix version since this directly impacts the roadmap, etc. For our project (Apache MyFaces) there are two level of users: regular users and developer. The developers are the only ones who can assign an issue to an individual, and ideally, they would be the only ones who can assign the verison to be fixed.
Its not really appropriate for the bug reporter to decide when the issue is fixed. I noticed the field is missing from this screen as I type so perhaps this is something that is already available?